Ram can afford to use their archers like that they are expendable, Wolfen units are significantly more expensive and losing one unit because he needed to get up close and personal isn't ideal. They can't just swarm the enemy unit that moves up to their archer with bodies. If an enemy moves into close quarters with your crossbowman theres a good chance that could be the end of him. The Assault crossbowman and the Herasser can overcome this situation thanks to their talents where as the Harpooner's profile lays him out as vulnerable to this situation. So he is very much a glass cannon which given that he is ranged and unable to counter or pursuit movement, he doesn't play so well to the wolfen's strengths.

With some support he might be worth it, but i'm not convinced. Maybe if he had impacable and it gave ranged units a single pursuit movement =P Or maybe if he had leg shot (i don't remember the name) to keep melee units at a distance.